African Wildlife & Environment Issue 79

CONSERVATION

Figure 2. Changes to precipitation represent an example of Mode “A” vulnerability as defined by the National Security Model (source Abatan et al., 2018).

was the academic work done by Professor Malin Falkenmark. Her model is shown in Figure 1 as it was adapted to inform the South African National Security discourse then underway. This model identifies four distinct modes of water scarcity. These are evident as circles with letters in them. The logic in the model moves from left to right, top to bottom, starting with environmental vulnerability. This implies that such vulnerability can be measured and quantified, so many new ideas began to emerge. Mode 'A' vulnerability is defined as the shortage of water needed to sustain biomass production arising from natural precipitation. This can be thought of as environmental flows, or water needed to sustain rainfed agriculture or natural ecosystems such as forests and grasslands. We can think of this as 'Green Water' for ease of discussion. Central to this is any shift in 'normal' rainfall events, which might cause a disruption to crop production. Currently we see this in South Africa as a distinct shift in winter rainfall (see Figure 2). Mode 'B' vulnerability is related to normal drought cycles but is potentially managed by storing water in dams. This water is known as 'Blue Water' for ease of discussion, and would only apply to some cropland, but not to natural

ecosystems other than in the form of a reduction of streamflow and modification of habitat. Mode 'C' is a distinct form of vulnerability, directly associated with desiccation of soils caused by improper agricultural practices. In this mode of vulnerability, soil water is directly associated with fertility and therefore biomass production, so it becomes a distinct form of national security risk. A direct consequence of Mode 'C' risk is a loss of national food security. Mode 'D vulnerability deals with water as a resource in rivers and dams. Due to the dependence on engineered systems, this form of vulnerability is directly linked to so- called Blue Water and has both an endogenous and exogenous component. The endogenous element includes aspects of eutrophication – the enrichment of water by sewage and agricultural runoff – which serves to create an induced scarcity. This limits options for economic development and thus becomes a distinct national security risk driven by unemployment, migration and potential mass uprising. Exogenous factors include changes to precipitation, such as that associated with global warming or climate variability, either natural or anthropogenic in origin.

16 | African Wildlife & Environment | Issue 79 (2021)